Dead front fused electrical connector



Dec. 29, 1970 D. B. ROBINSON 355mm DEAD FRONT FUSED ELECTRICAL CONNECTOR Filed June 14, 1968 2 Sheets-Sheet 1 J2 27/8 22 53 so 43 5 45 4.2 44 34 1 N VENTOR.

Donald RQbnsan.

Dec. 29, 1970 D. s. ROBINSON DEAD FRONT FUSED ELECTRICAL CONNECTOR 2 Sheets$heet 2 Filed June 14, 1968 Mm wk INVENTOR. Donald 6. Robinson.

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MN OK m9 United States Patent 3,551,869 DEAD FRONT FUSED ELECTRICAL CONNECTOR Donald Brown Robinson, 538 Iron Ave., Dover, Ohio 44622 Filed June 14, 1968, Ser. No. 737,063 Int. Cl. HOlh 85/48 U.S. Ci. 337201 9 Claims ABSTRACT OF THE DISCLOSURE An electrical connector having mating housings formed to establish a fused circuit and in which the line side housing has a dead front upon separation of the housings.

This invention provides an electrical connector having a pair of housings either of which can carry a fuse element in a manner to prevent the fuse from being electrically energized when the housings are mechanically separated.

The objects and advantages of this invention will become apparent to those skilled in this art upon consideration of the following detailed description and drawings of preferred embodiments in which:

FIG. 1 is a perspective view of the housings, in part, which form an electrical connector embodying the present invention;

FIG. 2 is a cross-sectional view of the connector shown in FIG. 1 as assembled;

FIG. 3 is a perspective view of a housing, in part, of another electrical connector embodying the present invention;

FIG. 4 is a cross-sectional exploded view of a connector formed by mating two identical housings of FIG. 3.

(FIGS. 1 and 2 illustrate one preferred embodiment of an electrical connector of the present invention comprising an elongated line side housing 12 mated with an elongated load side housing 34 each of which is formed from any suitable resilient insulating material, such as molded neoprene or rubber.

As shown, housing 12 has a cylindrical main body portion with a frusto conical rearwardly tapering end portion extending rearwardly therefrom. A coaxial cylindrical bore 14 extends axially rearwardly from a mating face 16 at the forward end of housing 12 to a rearward surface 17 and a forwardly open ended slot 22 extends rearwardly from surface 17 to a rear surface 18 with one extent thereof being equal to the inside diameter of the bore 14. The bore 14 and slot 22 are coaxial with the central longitudinal axis of housing 12. The sides of slot 22 have diametrically opposed forwardly open ended, laterally outward and longitudinally rearwardly extending cylindrical segments which in combination with slot 22 forms one portion of a fuse retainer chamber 19. The bottom of the slot 22 is spaced rearwardly from the inner end of chamber 19 to provide a pair of laterally spaced circular segment seating portions 13 at the inner end of the portion of the chamber 19 within housing 12. In practice a coaxial cylindrical wire receiving bore 28 of a diameter equal to the diameter of chamber 19 extends axially rearwardly through housing 12 from surface 18.

A generally U-shaped electrical bus strap 25 having a centrally disposed cup-shaped wire grip 27 suitably fixed to the bight portion thereof and extending oppositely to the arms thereof, is snugly received in slot 22. The open end of bus strap 25 is disposed rearwardly a short distance from rear surface 17 of bore '14 to insure a positive mechanical coupling with the load side housing as hereinafter described before the electrical circuit is completed. A portion of an insulated electrical cable 30 is snugly received in and extends through bore 28 with the free end being stripped of insulation and suitably electrically and mechanically connected to wire grip 27.

Housing 34 has a cylindrical main body portion with a frusto conical rearwardly tapering end portion extending rearwardly therefrom with an axially extending cylindrical through bore 36 having an intermediate enlarged diameter portion or chamber 38. Housing 34 has a portion 40 of a generally annular cross section having a reduced outer diameter relative to the main body portion thereof which extends axially forwardly from a mating face41 and which terminates in a forward annular surface 47. Forward portion 40 has an axial length and outer diameter substantially the same as the axial depth and inner diameter of bore 14 of housing 12, respectively, to enable bore 14 to receive portion 40 in the assembly of an electrical connector. A generally cup-shaped fuse grip 42 of an outside diameter equal to the diameter of bore 36 is closely received in chamber 38. Fuse grip 42 has a radially outwardly flared open end facing forwardly of housing 34 and is suitably sized to snugly receive one end of a fuse 43. The closed rear end of fuse grip 42 has a rearwardly extending centrally disposed cup-shaped wire grip 44 fixed therto. A helical coil spring 45 is disposed in chamber 38 around a forward portion of fuse grip 42, which spring provides a radially inwardly directed compressive force on fuse grip 42. A portion of an insulated electrical cable 46 is snugly received in the rearward portion of bore 36 and extends through to cham ber 38 with the free end being stripped of insulation and suitably electrically and mechanically connected to wire grip 44.

Forward portion 40 of housing 34 suitably supports an electrical contact 50. Contact 50 includes a circular collar portion 51, imbedded in the forwardmost portion of portion 40, of a diameter approximately equal to the central diameter of annular surface 47 with a pair of diametrically opposed flexible double contacts or prongs 52 and 53 afiixed to and extending forwardly thereof. Prongs 52 and 53 are bent slightly radially inwardly of collar 51 and at the forward most end thereof a 180 radially outward reverse bend is made thereby forming rearwardly extending contact engaging surfacse 54. With such configuration prongs 52 and '53 establish good electrical contact with bus strap 25 as is well known in the electrical contact art. The axial length from the front ends of prongs 52 and '53 to the closed rear end of fuse grip 42 is equal to or slightly greater than longitudinal length of a tubular fuse 43. Fuse 43 is of a type well known in the art having electrically conductive fuse end caps electrically connected by fusible conductor means (not shown) and spaced apart by insulating means.

In assemblying an electrical connector as described, fuse 43 is inserted between prongs 52 and 53 into bore 36 and into fuse grip 42 with sufificient axial force to overcome the bias of spring 45. Spring 45 provides a compressive force on fuse grip 42 sufiicient to insure a good electrical contact between fuse grip 42 and a fuse end cap 55 and to provide a retaining force on fuse 43 when housings 12 and 34 are separated. The resiliency of prongs 52 and 5-3 serve to provide a good electrical and mechanical contact between the prongs and a fuse end cap 55. The entire electrical connector is assembled by axially aligning housing 34 and housing 12 so that prongs 52 and 53 are aligned with slot 22. Body 34 and housing 12 are then forced together with fingers 52 and 53 entering slot 22 and engaging portions of the arms of bus strap 25. The bent portions of prongs 52 and 53 fiex and exert a compressive force on the arms of bus strap 25 which force aids in holding housing 12 and body 34 together. The portions of the outer end of the fuse 43 not in contact with prongs 52 and 53 are snugly engaged by the walls of chamber 19. The

3 inner surface of bore 14 and the outer surface of forward portion 40 can be provided with cooperating indexing means for the purpose of providing positive axial alignment between housings 12 and 34.

When housing 12 and body 34 are separated fuse 43 will normally remain in position in body 34. Since body 34 is the load side of the connector the fuse 43 may be readily removed without the hazard of injury occurring to the person removing the fuse 43. However, even if .fuse 43 remains in housing 12, which is the line side of the connector, or is inadvertently placed in housing 12, it may be removed without danger of injury since fuse 43 will be held in chamber 19 safely away from bus strap 25. Thus, fuse 43 can be inserted into either half of the electrical connector without being energized.

Various modifications can be made to the above described embodiment of the invention as those skilled in the art will readily recognize. For example, an electrical contact of a rigid construction can be used rather than the flexible contact 50. The operation of such a Contact would be by frictional means rather than compressive means.

FIGS. 3 and 4 illustrate another embodiment of an electrical connector of the present invention and includes a pair of identical elongated housings 70 which are formed of any suitable resilient insulating material, such as molded neoprene or rubber.

As shown, housing 70 has a cylindrical main body 72 with a frusto conical rearwardly tapering end portion 74 extending rearwardly therefrom. Main body 72 is provided with a generally semi-circular cross sectional shaped cavity 76 extending axially rearwardly from an annular mating face 77 thereof to an intermediate surface 78 which has the general cross-sectional shape of a 180 portion of an annulas having the outside diameter thereof equal to the inside diameter of cavity 76.

A nose portion 80 having a general cross-sectional shape equal to wall 78 and diametrically opposed therefrom, extends axially forwardly from the transversal plane containing the surface 78 to a front face 86 which is forwardly beyond mating face 77 a distance substantially the same as the axial depth of cavity 76.

A forwardly open ended slot 84 coaxial with the central longitudinal axis of housing 70 extends rearwardly from surface 78 to a rear surface 95 which is located between the ends of main body 72. The major transverse dimension of slot 84 is of a length equal to a distance slightly more than the inside radius of annular face 77 plus a distance slightly more than the inside radius of nose portion 80. The portion of slot 84 which extends below the inside radius of nose portion 80 is extended forwardly therefrom and terminates open endly at face 86 thereby forming a groove 88 in nose portion 80. The sides of slot 84 have diametrically opposed forwardly open ended, laterally outward and longitudinally rearwardly extending cylindrical segments which in combination with slot 84 form one portion of a fuse retainer chamber 105. The bottom of slot 84 is spaced rearwardly from the inner end of chamber 105 to provide a pair of laterally spaced circular segment fuse seating portions 92. In practice a coaxial cylindrical wire receiving bore 82 of a diameter equal to the diameter of chamber 105 extends axially rearwardly through housing 70 from surface 95.

A generally L-shaped bus strap 94 having a cup-shaped wire grip 96 suitably fixed to a rearward portion 107 thereof and extending rearwardly thereof is snugly received in slot 84 with the wire grip 96 disposed rearwardly within bore 82 and an axially extending leg 106 thereof disposed forwardly of bight portion 107, diametrically opposite of groove 88. A portion of an insulated el ctrical cable 98 is snugly received in and extends through bore 82 with the free end thereof being stripped of insulation and suitably electrically and mechanically connected to wire grip 96.

A longitudinally forwardly extending electrical contact 100 is embedded in the nose portion 80', parallel and directly below groove 88 and has a forwardly extending double contact prong portion 101 which has the top surface thereof in the same plane as the inside surface of nose portion 80. Prong portion 101 extends forwardly of front face 86 and at the forward most point thereof a radially outward reverse bend is made thereby forming a rearwardly extending contact engaging surface 102. With such configuration prong 101 will establish good electrical contact with the axially extending leg 106 of bus strap 94 of a mating housing 70, as is well known in the electrical contact art.

The diameter selected for the fuse retainer chamber is suitable to snugly receive a fuse 104.

The axial length from the front end of prong 101 to the fuse seating portions 92 is equal to or slightly greater than the longitudinal length of a tubular fuse 104. Fuse 104 is of a type well known in the art having electrically conductive fuse end caps 55 connected by fusible conduct ing means (not shown) and spaced apart by insulating means.

In assembling the electrical connector of FIGS. 3 and 4 the cable 98 in one housing 70 is wired to the load side of a circuit (not shown) and the cable 98 of the mating housing 70 is wired to the line side of that circuit. Fuse 104 is inserted in either housing 70. Since fuse 104 will not directly engage a bus strap 94 there is no danger of injury even if the fuse 94 is placed within the line side housing 70. The housings 70 are axially aligned with the nose portion 80 of one housing 70 rotated with respect to the nose portion 8 0 of a mating housing 70. The housings 70 are brought together so that the fuse 104 enters the fuse retainer chamber 105 of the housing 70 not having the fuse 104 therein. The respective contacts 100 will enter into the respective slots 84 so that the contact engaging surfaces are electrically and mechanically engaging the respective axially extending legs 106 of bus straps 94. When the housings 70 are securely mated complete electrical engagement will exist between the respective cables 98, bus straps 94 and contacts 100. When the housings 70 are separated the fuse 104 will remain in one of the housings 70, but as indicated previously, the fuse 104 will not be in engagement with the bus strap 94 of the housing 70 in which the fuse 1-04 remains.

The material selected for the contacts and bus straps must have the physical propery of being a good elec' trical conductor. In addition, the contacts must be formed from a sufficiently resilient material which will allow the prongs to flex when a fuse is inserted therebetween and to permit the contact engaging surface to flex when the prongs engage the arms of the bus straps.

The connectors described are single pole but these can easily be ganged into a common body to make a multipole device. The housings and bodies of the connectors were described as resilient but can be made of rigid phenolics, nylons or the like with slight adjustments for retaining the internal elements.

The significant feature of this invention is the fact that connector is a dead-front fused connector in that the fuse is not electrically energized by the line side when the housings of the connector are physically separated. An added advantage is manifest in the second embodiment described, that being that the housings of each side of the connector are identical thereby eliminating the need for manufacturing two distinct housings in order to make a connector.

While preferred embodiments have been shown and described it is to be understood that those skilled in the art can modify the structure of such embodiments without departing from the inventive concept described herein.

What is claimed is:

1. An electrical connector comprising a connector housing consisting of a pair of selectively matable insulating bodies, one of said bodies having an open ended cavity extending inwardly thereof, the other of said bodies having a protruding portion closely received within the outer portion of said cavity, electrical conducting prong means carried by said protruding portion and extending from a surface thereof into said cavity, said cavity having a first electrical contact therein engagable with said prong means within said housing, said other of said body members having an elongated bore in open communication with said surface a second contact located within said bore inwardly of said surface, and said first and second con tacts being connectable to electrical conductors respectively and said prong means and said second contact be ing of a form and spaced from each other to be able to at least electrically engage end portions of a known elongated fuse.

2. An electrical connector as specified in claim 1 where in, said second contact is a cup-shaped element and said first contact is a U-shaped element.

3. An electrical connector as sepcified in claim 2 wherein, each said prong means is a double contact element With two spaced contact portions resiliently connected to make contact between said first contact and one of said fuse end portions.

4. An electrical connector as specified in claim 3 wherein said prong means comprises two diametrically opposed double contact portions engageable between one of said fuse end portions and said first contact.

5. An electrical connector as specified in claim 1 wherein, said cavity has a portion wormed to closely receive one such fuse end portion.

6. An electrical connector comprising; a separable connector housing consisting of a pair of identical elongated insulating bodies having interfitting end portions, each of said end portions having a protrusion extending longitudinally therefrom, and a longitudinally inwardly extending cavity which receives said protrusion of the other of said bodies therein, electrically energizable contact means mounted within each of said cavity portions, said protrusions having electrically conducting prong means extending therefrom engageable with said electrical con tact means respectively, said housing having means to receive a known elongated fuse element having axially spaced conducting end portions and said prong means being spaced longitudinally from each other and of a form to engage the conducting end portions, respectively, of such a fuse element whenever such fuse element is received within said housing.

7. An electrical connector as specified in claim 6 wherein the prong means of each body is a double contact prong means extending outwardly from said protrusion and each electrically energizable contact means is an L-shaped contact connectable to one of said conducting end portions by said prong means on the other of said bodies.

8. An electrical connector as specified in claim 6 wherein, said pair of insulating bodies comprises two identical bodies having identical components therein.

9. An electrical connector as specified in claim 6 wherein, the inner surfaces of said protrusions of said identical bodies form an elongated reduced diameter cavity shaped to closely receive such a fuse element.

References Cited UNITED STATES PATENTS 3,377,610 4/1968 Busch et al. 339-147X 2,700,085 1/1955 Breisch et al 337-201 BERNARD A. GILHEANY, Primary Examiner D. M. MORGAN, Assistant Examiner US. Cl. X.R. 339 147 

